On a cold day in mid-December 2011, a hacker known as "sup_g" sat alone at his computer – invisible, or so he believed. He'd been working on the target for hours, long after the rest of his crew had logged off: an epic hack, the "digital equivalent of a nuclear bomb," as it later would be described, on the servers of a Texas-based intelligence contractor called Strategic Forecasting Inc. Stratfor served as a sort of private CIA, monitoring developments in political hot spots around the world and supplying analysis to the U.S. security establishment.

A member of the online activist movement Anonymous, sup_g was part of a small team of politically motivated hackers who had breached Stratfor's main defenses earlier that month – ultimately "rooting," or gaining total access to, its main web servers. In them, they had found a cornucopia of treasure: passwords, unencrypted credit-card data and private client lists revealing Stratfor's deep ties to both big business and the U.S. intelligence and defense communities. But perhaps the most lucrative find of all was Stratfor's e-mail database: some 3 million private messages that exposed a wide array of nefarious and clandestine activities – from the U.S. government's monitoring of the Occupy movement to Stratfor's own role in compiling data on a variety of activist movements, including PETA, Wikileaks and even Anonymous itself.

And now, finally, it was done. Logging on to a secure Web chat, sup_g sent a message to a fellow activist. "We in business, baby," he said. "It's over with."

One of the most radical and committed hackers in the shadowy world of Anonymous – a leaderless, nonhierarchical federation of activists with varying agendas – sup_g kept a low profile within the group, carefully concealing his real name and maintaining a number of aliases. That June, he had joined a new faction within Anonymous known as Operation Antisec, or #Antisec, which described itself as a "popular front" against the "corrupt governments, corporations, militaries and law enforcement of the world." Though hundreds of activists may have frequented its internal communication channels, known as Internet relay chats, Antisec had less than a dozen core members: hackers, anarchists, free-speech activists and privacy crusaders, as well as "social engineers" – skilled manipulators whose talents lay in tricking even the most security-conscious into giving up their passwords or other data. The founder and most prominent member of Antisec was a bloviating, heavyset 29-year-old hacker, self-proclaimed revolutionary and social engineer known as "Sabu," who had a special loathing, it seemed, for the intelligence industry. "Let us show them we can spy on them too," he'd tweeted to his more than 35,000 followers in early December.

For three weeks, sup_g and his crew had worked steadily to ruin Stratfor, one of their biggest and richest targets yet. In addition to supplying geopolitical analysis to everyone from the Pentagon to the United Nations, the firm provided customized security services for leading companies like Raytheon and Dow Chemical, often compiling dossiers on activists and others viewed as threats to corporate profits. By Christmas – which Antisec dubbed "LulzXmas" for the "lulz," or mocking enjoyment, they intended to have at Stratfor's expense – the group had made off with more than 200 gigabytes of data. They then destroyed the company's databases and defaced Stratfor's website with a triumphant message promising a "week of mayhem" that would include posting the firm's secrets online – some 860,000 names, e-mails and passwords, including several dozen belonging to top-secret operators whose identities were now leaked for the very first time. Antisec also planned to use the hacked credit cards to make donations to groups like CARE and the American Red Cross. As an added flourish, the group ended its communiqué with the full text of the influential French anarchist tract The Coming Insurrection. "It's useless to wait . . . for the revolution," the treatise reads. "The catastrophe is not coming, it is here."

Three months later, on the evening of March 5th, 2012, more than a dozen federal law-enforcement officers broke down the door of a small brick house on the southwest side of Chicago and arrested Jeremy Hammond, a 27-year-old anarchist and computer hacker they believed to be sup_g. Six feet tall and lanky, dressed in a purple T-shirt and ratty trousers – a signature style one of his female friends noted was less Salvation Army than "the free box outside the Salvation Army" – Hammond looked more like a crusty punk than a computer nerd. In fact, he was both, as well as many other things: an inveterate "black hat" hacker, an irrepressible agitator and enemy of the "rich, ruling class" who identified with the ideas of the Weather Underground and considered the Occupy movement too tame.

Even before the arrest broadcast his name worldwide, Hammond was well-known in extreme-left circles. An early champion of "cyber-liberation," he had been described by Chicago magazine at the age of 22 as an "electronic Robin Hood" after he was sentenced to two years in federal prison for hacking a conservative website and making off with 5,000 credit-card numbers, intending to charge donations to progressive causes. But unique within the hacking subculture, Hammond was also a real-life revolutionary: a "modern-day Abbie Hoffman," in the words of his friend Matt Muchowski. He possessed a shrewd intelligence as well as a certain impulsivity – a fellow hacker referred to it as "urgency" – that had led to a long string of civil-disobedience arrests dating back 10 years, for offenses ranging from defacing a wall with anti-war slogans to banging a drum during a "noise demo" at the 2004 Republican National Convention in New York. (He later called his brief stint in the Tombs his "best prison experience.") Hammond was even busted once, in 2005, for trying to join a protest, against a group of white supremacists in Toledo, Ohio. "They hadn't even gotten out of the car when they were arrested," says Muchowski, a Chicago union organizer who bailed Hammond out.

His arrest, the most prominent bust to date of a U.S. hacktivist, was also a major coup for the FBI. Before Hammond was locked up, Anonymous had engaged in a year-and-a-half-long hacking spree, waging a full-scale war against the "rich and powerful oppressors." The group shut down the websites of the CIA, major banks and credit-card companies. They took up the cause of the Arab Spring by attacking the government websites of Libya, Tunisia and Egypt; they broke into computers belonging to NATO and the GEO Group, one of the world's largest private prison corporations. They hacked defense contractor Booz Allen Hamilton – an attack, dubbed "Military Meltdown Monday," that yielded 90,000 military and civilian e-mail accounts and passwords. They even attacked the FBI itself.

But none of these attacks had the political resonance of Stratfor. The computer breach not only cost the company millions, but focused worldwide attention on the murky world of private intelligence after Anonymous provided the firm's e-mails to WikiLeaks, which has been posting them ever since. It was, by any estimate, an audacious hack – and one for which Hammond may face decades in prison.

Hammond, who has never admitted to any of the nine nicknames the government claims he operated under, has pleaded innocent to the Stratfor hack. But he has not disavowed his involvement with Anonymous, nor his desire to "push the struggle in a more direct action, explicitly anti-capitalist and anti-state direction," as he wrote to me from Manhattan's Metropolitan Correctional Center, where he has been held for the past eight months awaiting a bail hearing. Indeed, his hallmark as an activist has always been his revolutionary, militant rhetoric, for which he is unapologetic. "I have always made it clear that I am an anarchist-communist – as in I believe we need to abolish capitalism and the state in its entirety to realize a free, egalitarian society," he wrote. "I'm not into watering down or selling out the message or making it more marketable for the masses."

This unwavering commitment, one of Hammond's greatest strengths, would also be what led to his undoing. He was always aware that betrayal was only a click away. "We know we'll finish in prison," says a hacker who worked with him. "Jeremy knew he was going to be raided, which is why he worked so quickly. He wanted people to remember him." What Hammond never suspected was that his downfall would come at the hands of one of his closest and most trusted allies.

It's an early-june morning at the Metropolitan Correctional Center, and Hammond walks into the small room usually reserved for lawyer-client conferences wearing a baggy brown prison jumpsuit meant for someone twice his size. In person, Hammond comes off as far less strident than he does on the page. He's friendly, but cautious. After 10 years of activism, he is a seasoned veteran of jails and rough treatment at the hands of the police.

"Hey," Hammond says calmly, "I'm Jeremy." He's a pale kid, nearly 28, with huge blue-green eyes, a wispy beard, and tattoos on each forearm – one, a tic-tac-toe-like symbol known as the "glider," is an emblem of the open-source movement; the other, the shi hexagram from the I Ching, "can be interpreted as the leader of a people's army," he explains. He looks tired. "I'm on a terrorist watch list," he tells me. "Hard to say what for, or how they monitor these terrorists." He flashes me a wan smile that says "prison sucks."

Since arriving here in March, Hammond has tried to keep busy teaching math to inmates who are studying for their GEDs, playing chess and reading anything he can get his hands on – most recently Love and Struggle, ex-Weatherman David Gilbert's prison memoir. But being locked up is both a "dehumanizing" and also excruciatingly boring experience, he says. Aside from his lawyers, I am the only visitor he's been permitted in three months.

Hammond was raised with his twin brother, Jason, in Glendale Heights, Illinois, a working-class town in the western suburbs of Chicago. His parents, Rose and Jack, never married, and when the twins were three, their mother moved out and later fell in love with a next-door neighbor, leaving the boys in the care of their father. According to Rose, who remained close to her sons, Jack Hammond was "a borderline genius" who had dropped out of high school to pursue a music career and had never wanted children "until the moment he laid eyes on the twins. Then his whole life was about them."

Jack was part of the Chicago alternative scene of the 1980s that spawned iconic punk auteur Steve Albini. He raised his boys, who were nicknamed "Hanson" because of their long hair, to pursue whatever path appealed to them. Jason, a sensitive jokester, was a musician like his father. Jeremy, the quieter, more thoughtful of the two, was the schemer – the little boy who, at two, climbed to the top of the kitchen pantry to retrieve money he'd seen his mother hiding there. Jack, who earned about $35,000 a year as a guitar teacher and received child support from Rose, would later say he and the boys were "the world champs of living cheaply and well" in a do-it-yourself kind of way.

This didn't always go over well in Glendale Heights – an area Hammond's friend Matt Muchowski describes as "part Rust Belt, part Disney World. There are a ton of Walmarts and Niketowns, so what you get growing up is a pod-person mentality: The only job that's there for you is at the mall."

A math and science whiz with an IQ of 168, Hammond "talked so fast it was like his mouth couldn't keep up with his brain," says one friend. At home, with no women around, the two brothers spent endless hours building cities with their immense Lego kits, or devouring the books in their dad's extensive library, which ran the gamut from Fight Club and The Catcher in the Rye to Abbie Hoffman's Steal This Book and Revolution for the Hell of It.

From an early age, Jeremy was consumed by projects in which he could lose himself. In Little League, he created a virtually unhittable pitch, and by the time he was nine, he was finding innovative ways to make computers do what they weren't supposed to do – the essence of hacking. At 16, he hacked the computers at a local Apple store, projecting their financial data on every screen, after which he proceeded to explain to the experts at the Genius Bar how to better protect their information. "The look on their faces was priceless," his father recalls.

At Glenbard East High School in nearby Lombard, Illinois, the Hammond twins were part of a crowd of "very smart kids looking for something more than they'd find in high school," as one friend, Matt Zito, recalls. Politicized, like many, by the attacks of 9/11, Jeremy was an outspoken critic of the Bush administration and the "blind patriotism" he saw as leading the U.S. to war. In his senior year he founded an underground newspaper to encourage students to question the conventional political narrative "and most of all think," as he wrote in his first editor's letter. "WAKE UP . . . Your mind is programmable – if you're not programming your mind, someone else will program it for you."

Hammond's mind was a hive of counter-cultural ideology, notably the modern-day insurrectionary ideas of CrimethInc, the anarchist collective and publisher of radical how-to guides, including its own take on The Anarchist Cookbook, titled Recipes for Disaster. Hammond romanticized the Sixties, says Zito, who worked with him on the newspaper. In the spring of 2003, on the first day of the Iraq invasion, Hammond led a walkout of more than 100 kids to an anti-war rally in downtown Chicago. That fall, he enrolled at the University of Illinois-Chicago and quickly became a powerful activist voice on campus – so much so, recalls his friend José Martín, that the administration once abruptly cut the mic while he attempted to give a speech. But Hammond lasted only a year at UIC. "Jeremy was fearless – or foolish, depending on how you look at it," says Pong Kay, who dated Hammond for two years. A pretty freshman, she'd met him at a campus bus stop where Hammond was writing graffiti advertising a protest he was organizing against university tuition hikes. Before long, he was taking her on expeditions to an abandoned drawbridge, which they'd scale, getting stoned at the top before laughingly making their way down.

The artsy daughter of Thai immigrants, Pong was smitten. "There was something incredibly charismatic about him," she says. "He was this young, hot-headed, hyperintelligent guy with a very low tolerance for authority, and this big heart – he had this core belief that human beings are inherently good."

Hammond was also, she adds, "trusting" – sometimes to his detriment. During the spring of his freshman year, he hacked into the computer-science department's website, identifying a vulnerability that, just as he had at the Apple store, he offered to fix. Instead, the hack earned him a disciplinary hearing and a letter from school administrators saying that he would not be welcomed back at UIC for his sophomore year.

What he learned, notes one friend, is that "if you try to work with the system, they fuck you over." And so, from then on, Hammond would dedicate himself to working outside it. Over the next few years, he threw himself into the day-to-day life of the radical community in Chicago, renting houses that quickly became crash pads for any homeless kid or traveler who happened through. Always the first to offer a toke or some food, he became famous for taking friends on epic dumpster-diving expeditions to hidden outposts like a local Odwalla plant, where, after plundering the refuse, he'd return with enough fresh juice to last a month. At night he'd settle in with "riot porn" – Internet clips of black-clad anarchists facing off with the police.

He became a fixture at virtually every major demonstration, as well as many minor ones. Clad in ratty jeans and a T-shirt "for some punk band whose biggest show was for 20 people at a basement benefit for an animal-rights group," as Muchowski puts it, Jeremy and Jason, now his comrade in anarchy, would arrive with a marching band – drums, horns, a tambourine or two – dancing and singing and generally annoying the more earnest demonstrators. "Boredom," he would later write, "is counterrevolutionary. Your movement needs to be fun . . . or no one will want to participate."

Hammond also "brought the ruckus," as he put it, in a more serious way: joining the militant and masked black bloc anarchists, getting into scuffles with cops and amassing an impressive rap sheet. Between the ages of 18 and 21, he was arrested 10 times in three different states.

But Hammond was more than just a street-level agitator. He was equally active online, part of a new, and to U.S. law enforcement, threatening generation of political activists. "These are guys who can travel seamlessly between cyberspace and meat space, without even recognizing much of a difference," says Steve Rambam, a New York cybersecurity investigator. Hammond's primary weapon, which few if any of his anarchist friends knew about, was a hacker boot camp of sorts, a website he'd developed called Hack This Site, which within two years had become a full-fledged online community with more than 100,000 members. It was here that Hammond began to meet so-called black-hat hackers who worked below the radar to take down websites for fun or profit, or sometimes both. "These people had large amounts of power – where one hacker could outsmart a whole company," he recalls. Street activists had very little power – but they had the politics to power the revolution. What if these two worlds could merge? "I thought hacking could be a tool – a weapon to disrupt abusive corporations."

Selling this idea wasn't easy. In the mid-2000s, there was little crossover between hackers and activists. Hammond wanted this to change. "Considering today's political climate, it is becoming imperative that we tune into the world around us, take a stance and give a fuck," he wrote in the first issue of a new "electronic civil-disobedience journal" called Hack This Zine, which he launched in the summer of 2004. He began to lay out an argument for international movement – "an army so powerful we won't need weapons," as Hammond put it. "If corporations and governments are out of line today, it's up to cowboys of the electronic age to turn over the system and put the people on top."

In July 2004, Hammond took his message to the annual DefCon hacker convention in Las Vegas, the largest convergence of hackers in the United States. There he made an impassioned speech praising the virtues of electronic civil disobedience as an effective tool to disrupt the upcoming Republican National Convention. "We'd like to see every method of disruption possible, whether it be shutting down the power to Madison Square Garden, or defacing 10,000 different Republican websites. . . . We'd like to see RNC delegates get harassed on the streets," he said. "Fuck 'em up! Shut 'em down!" Some people in the audience jeered, and one person asked if what Hammond was proposing amounted to terrorism. "One man's freedom fighter is another man's terrorist," he scoffed. "Let them call us terrorists; I'll still bomb their buildings."

Soon after he returned to Chicago, FBI agents who had seen a tape of the DefCon speech paid Hammond a visit to ask him if he really intended to bomb the Republican convention. Hammond said he had been engaging in a bit of radical hyperbole – though he had begun to envision a digital insurgency of sorts: an "Internet Liberation Front," which, much like the radical environmental and animal-rights groups ELF and ALF, would organize as underground cells and use nonviolent "hit and run"-type tactics to attack the "rich and powerful."

An early target was a group called Protest Warrior, a Texas-based pro-war organization that had a habit of showing up to rallies to heckle left-wing activists. In February 2005, Hammond and some fellow hacktivists breached the organization's website, gaining access to thousands of credit-card numbers they wanted to charge in order to redistribute the wealth to left-wing causes. Protest Warrior notified the FBI, which raided Hammond's apartment that March. The Bureau spent the better part of the next year building a case against him, though as Hammond would repeatedly note, he never actually charged anything to the cards.

Hammond ultimately confessed to the hack and was sentenced to two years at the Federal Correctional Institute at Greenville, Illinois, about 250 miles from Chicago. He doesn't speak very much about Greenville, but his mother suggests it was a far cry from the Cook County jail, where he had been held on numerous occasions. "The first time I went to visit him, he'd been there less than a month and he was trembling," she says. "He told me, 'Mom, when I get out, I'm going to be a better person.' He was scared. I thought, 'This is not my Jeremy.'"

By the second time she visited, Hammond was no longer trembling. He'd begun his "training," as he would refer to his time in prison, conditioning himself "mentally and physically" to become a more effective freedom fighter. He immersed himself in radical literature like Alexander Berkman's Prison Memoirs of an Anarchist and the autobiographies of Black Panthers George Jackson and Elaine Brown, and read countless anarchist newsletters that were passed along through prison channels. Among his influences was the former Weather Underground leader Bill Ayers, who had taught at UIC when Hammond was a student. "Live your life in a way that doesn't make a mockery of your values," Ayers wrote in his memoir, Fugitive Days. "Wherever injustice raises its head, resist; the revolution is your permanent vocation."

He emerged from Greenville 18 months later a changed man. "He seemed angry and really militant," says his former housemate Scott Scurvy, who points out that before going to prison, Hammond had an almost Merry Prankster-like take on activism. Now, "he was talking about 'cracking skulls' on people he perceived as racist or homophobic. He kind of tripped me out."

The consensus among many of their friends, Scurvy says, was that "prison sort of messed him up." But others realized it as a form of clarity. "There are two paths you take after you come out of prison," says Jason Hammond. "Some people go straight and try to achieve the American dream, and others go, 'Fuck it, the whole idea is bullshit, as is the system that created it,' and they go in a more radical direction. And Jeremy took that path."

In the summer of 2008, Hammond returned to Chicago and what was supposed to be a new life. With Jason and some friends, he moved into the fourth-floor apartment of a ramshackle house in Pilsen – "sandwiched between the two finest dumpsters in Chicago" – that they dubbed "Mount Happy," and went to work as a web designer. He was barred, by the terms of his release, from associating with anarchists or his old colleagues at Hack This Site for the next three years. And yet he was unable to walk away from his politics altogether. So he turned to mainstream activism, joining the Chicago branch of the Rainforest Action Network, where he helped organize a campaign to shut down two local coal plants. "He'd ride this rickety bike all the way across town," says Lyn Michaud, who founded the city's chapter of RAN, "probably an hour each way, to attend meetings that would last four or even six hours."

Hammond, she adds, "wasn't just anti-capitalist in words; he walked the talk. We would have a meeting at a restaurant, and Jeremy wouldn't buy food – he'd eat other people's leftovers. I'd be sitting there, like, horrified, but he'd just casually walk over to an empty table, grab like half a plate of leftover food and bring it over. He literally lived off the waste of others."

Michaud, 10 years older than Hammond, took Jeremy under her wing, inviting some of the world's most well-respected activist trainers to meet with her group in Chicago. Once she even invited Hammond's hero, Bill Ayers, to a potluck dinner. Jeremy was star-struck. "He called him 'sir,' " she recalls, laughing. "That was funny: This big anarchist who was so anti-hierarchy called Bill Ayers 'sir.'"

Ayers recalls Hammond as one of a group of "terrific and supersmart young people" who engaged in "a lively discussion about activism." But Hammond's politics were far more radical than the activists with whom he now associated, and he could be scathing with those that he felt lacked the sufficient revolutionary cred. The idea of willingly getting arrested as an act of civil disobedience puzzled him – "The revolution to me is about not getting in their jails," he says – as did the seemingly endless process of petitioning local officials and holding sit-ins that got no attention.

Hammond's adventure with "polite activism" lasted just more than a year. Frustrated, he was drawn back to militancy and, in turn, to trouble with the law. At a rally in September 2009 to protest the city's plans to host the 2016 Olympics, Hammond and his brother were arrested after engaging in a tug of war with an Olympic banner, "in which various parts were burned, right in front of the media cameras," he says. "In retrospect, it was an impulsive, poorly planned-out action with no exit strategy." Worse, it was also a clear violation of his probation. A week later, Hammond, out on bail, joined some comrades in breaking up a talk given by British Holocaust denier David Irving, where, dressed all in black, they heckled Irving and doused his books in fake blood before making their escape. But they were quickly apprehended.

Hammond narrowly avoided being sent back to prison. He accepted 130 hours of community service and 18 months of "enhanced probation," which meant he could be visited – he and his friends would say "raided" – by his probation officer and the Chicago police at any time, and his home and possessions thoroughly searched. He was unable to leave the state of Illinois, and he was put on a 7 p.m. to 7 a.m. curfew. About the only place he could still travel freely was online.

In January 2008, during Hammond's last six months at Greenville, the famously controlling Church of Scientology "angered the Internet," as it was said, by trying to remove a controversial Tom Cruise video from the Web. In response, the Internet – or more specifically a loose coalition of Internet denizens calling itself Anonymous – released its own video, where, in a computerized voice, it declared war on the Church. You have nowhere to hide because we are everywhere, the message said in part, ending with the lines that would become the collective's slogan:

We are Anonymous. We are legion. We do not forgive. We do not forget. Expect us.

At first, Anonymous seemed like little more than a group of malicious pranksters, enraged over Internet censorship. They began targeting groups like the Recording Industry Association of America, which was waging a campaign against online piracy, and the Australian government, which had proposed a filter for online pornography featuring underage girls. (Anonymous dubbed the attack Operation Titstorm.)

In Chicago, Hammond was aware of Anonymous but had dismissed it. "I didn't take them seriously. These weren't, like, super-voodoo hackers," he says. But he began to realize the political potential of Anonymous once they launched Operation Avenge Assange in December 2010, shortly after PayPal, Visa, MasterCard and several other financial institutions abruptly stopped processing donations to Wikileaks, which had come under fire for publishing the diplomatic cables leaked by Bradley Manning. Organizing online, Anonymous held what electronic-freedom activists call a "digital sit-in," encouraging thousands of people to download an online tool called the Low Orbit Ion Cannon, or LOIC, to bombard the companies' websites and knock them offline.

"This spontaneous gathering was one of the first large-scale demonstrations conducted on the Internet," says Gabriella Coleman, a professor at McGill University considered the foremost expert on Anonymous. It also marked the beginning of a new chapter for the group, "providing a paradigm for general online protest that would soon allow individuals to unite and organize to express their deep disenchantment over any and every issue."

Hammond was impressed. "They were taking on credit-card companies and banks," he says. "I thought maybe there were people there who recognized who the bigger enemy was and how to fight them."

One of those people who seemed drawn to the larger struggle was a hacker named Sabu. Born Hector Xavier Monsegur in 1983, he'd grown up in a family of drug dealers – both his father and his aunt went to prison for heroin trafficking in 1997 – and was raised by his grandmother Irma in the Jacob Riis projects of New York's Lower East Side. A husky, bookish kid, he'd never really fit in among the gangsters and street hustlers of his mostly Puerto Rican neighborhood, but he had a natural gift for computers, as well as a rebellious streak. At 14, around the age that Hammond was wowing the Apple "geniuses," Monsegur, whose family couldn't afford an Internet connection, had figured out a way to get on EarthLink for free and proceeded to teach himself Linux, Unix and open-source networking. When he was 16, he defaced several Puerto Rican government websites after a U.S. Navy live-fire exercise on the island of Vieques accidentally killed a local civilian. But he was also an opportunist.

Where Hammond saw hacking as a tool in the larger struggle, Monsegur saw hacking, and its legitimate counterpart, white-hat Internet security consulting, as a way out of the struggle he lived day to day. He craved "respect," as he frequently noted online, and as a kid had landed coveted spots in several New York City-run IT programs for underprivileged teens. In his early 20s, he'd freelanced for a Swedish Internet security firm and later worked for the peer-to-peer file-sharing company LimeWire. But by 2010, Monsegur, now 26 and the sole guardian of two small cousins he called his "daughters," was drifting, living on public assistance in the same projects in which he'd grown up. He sold marijuana on the street, and fenced stolen goods. He also began hacking for profit: stealing credit-card numbers to pay his bills, and hacking into an automotive-parts company, where he ordered four engines worth close to $3,500 for his cars, including a vintage Toyota AE86, which he named "Revolution."

Before long, Anonymous gave Monsegur a mission – he'd later say it was a movement he had been waiting for his entire life. Calling himself Sabu, he began working his way through the various Internet relay chats (IRCs) in Anonops, the IRC network where hacktivists gathered, into the smaller, private chat rooms where illegal actions were planned. When the Middle East exploded in January 2011, he eagerly took part in what Anonymous called the "Freedom Ops": waging war, from his computer, on the websites of the oppressive governments of Tunisia, Egypt, Syria, Libya and Bahrain. Yet, unlike Hammond, whose revolutionary ideology infused every aspect of his life, Sabu's nobility of purpose was limited. His main cause, now as always, was himself. "Sabu," one hacker later noted, "believes in Sabu."

FBI surveillance of Anonymous began, by most accounts, around 2010. "In the beginning, nobody in law enforcement even knew who Anonymous was," says one former member. "To the FBI, they'd just been this Scientology nuisance. So when Anonymous started coming out in support of Assange and Bradley Manning, they were really behind. They didn't understand the culture at all."

To help the government – and, he hoped, to win contracts for his firm, HBGary Federal – a digital-security analyst named Aaron Barr decided that he would figure out the secret "leadership" of Anonymous. In early 2011, after studying the group for weeks and lurking in Anonymous chat rooms, Barr drew up a 20-page document with the names and contact information of a number of people he believed formed Anonymous' central core. He then went public, telling a reporter from The Financial Times that he'd unlocked the mystery of Anonymous, which he intended to broadcast widely.

Though Barr's document turned out to be riddled with mistakes, Anonymous took his threat seriously. On Super Bowl Sunday, February 6th, 2011, Sabu and his crew, which called themselves the "Internet Feds," hacked into HBGary's website, Barr's Twitter account and also the company's e-mail database, extracting 68,000 e-mails, which they posted to popular file-sharing site the Pirate Bay. Within a day, news of the hack was everywhere – Steven Colbert famously devoted a segment of The Colbert Report to the hack: "To put that in hacker terms," he said, "Anonymous is a hornet's nest, and Barr said, 'I'm going to stick my penis in that thing.'"

The HBGary hack wound up being more than a bit of payback: Barr, it turned out, had been gearing up a "dirty tricks" campaign against pro-WikiLeaks journalists like Salon's Glenn Greenwald. He'd also pitched the U.S. Chamber of Commerce on how to discredit labor unions and liberal groups. The leak of Barr's e-mails resulted in his resignation and also caused 17 members of Congress to push for an investigation into HBGary's activities.

Watching this go down, Hammond was amazed. "It was an epic hack," he says. Sabu, who took credit – a bit too much credit, many thought – intrigued Hammond. Unlike other Anons, Sabu talked a tough game, using ghetto slang like "my nigga," and shared Hammond's loathing for the police. He even hinted at a criminal past. "I've been to jail before – I don't fear it," he wrote in one online post. "I've been in the game for over a decade."

Says one of Hammond's Chicago friends, "I can totally imagine Jeremy digging the fact that he befriended a hacker from the hood."

Few people in the movement expressed themselves with such passion, and all Hammond could see was a fellow hacktivist down for the cause. "He put the work in; that's why I respected him," Hammond says. "And I trusted him too." It wasn't initially clear why. Most longtime hackers prefer to work in the shadows, never letting anyone know who they are. Sabu bragged about his talents, awing younger Anons, many of them teenagers, with tales of his "Puerto Rican hacking crew" from the late 1990s and his subsequent years "underground." "He made it seem like you were in this supersecret revolutionary group and portrayed himself as this silent underground hero who was risking everything to make a difference," says one former acolyte.

Hammond, too, was drawn in by Sabu's rhetoric. "He seemed to understand, more than most Anons, what the root of the problem really was," Hammond says. "I'd sit in IRC watching these arguments go down – just stupid shit people would say. But there were some people who got to the baseline element and said things like, 'We must destroy capitalism. We must destroy their systems.' That interested me."

But the random malice that Anonymous, and Sabu's crew in particular, unleashed turned off many, including a 40-year-old Michigan mom and longtime Internet denizen named Jennifer Emick, who had come to believe that some of the more ideologically driven Anons might be dangerous. Shortly after HBGary, Emick decided to do what Aaron Barr had failed to do: She outed, or "doxed," a number of key Anons, including Sabu, publicly listing his name and the neighborhood he lived in. This was perhaps the worst thing that could happen to a hacker, striking a blow to his pride, as well as to his much cherished invisibility – removing the protection that's made Anonymous so powerful to begin with, and leaving him vulnerable to government tracking and, ultimately, arrest.

Sabu denied she'd gotten him, taking to Twitter and issuing a passionate cri de coeur, in which he reminded all Anons that they were "part of something powerful," urging them not to "succumb to fear tactics" and to "stay free."

In many ways, Anonymous, with its nonhierarchical structure, was the realization of what Hammond had always wanted to create – indeed, his 2004 DefCon speech provided the blueprint for what the hacktivist collective became. But Anonymous activism was different than real-world activism, where flesh-and-blood true believers like Hammond could develop passionate followings. In the faceless, nameless online world where no one knew who anyone was, it was the trolls and the liars, the social engineers like Sabu, with a remarkable capacity for duplicity, who spoke the loudest. "It's extremely easy to manipulate people online if you just know how," says one former Anon. "The whole point of IRC is that you can be anyone you want: a revolutionary, a troll, an FBI agent."

Over the coming months, as Hammond's interest grew, Internet Feds morphed into a splinter group called Lulz Security, or Lulzsec. It was led by Sabu with support from a talented propagandist named Topiary. Between May 7th and June 25th, 2011 – dubbed the "50 Days of Lulz" – Lulzsec attacked multinational corporations, gaming sites and several porn sites. Each action was announced with splashy, theatrical bits of PR: a fancifully worded press release and hyped-up Tweets, all designed to garner maximum attention. The media rushed to declare Lulzsec "cyber-vigilantes." New York magazine would later describe them as the Internet's "SEAL Team Six."

The hacks were so spectacular, and came so fast, that few Anons noticed that Sabu went missing for a full 24 hours in June, something he'd never done before. When he returned to IRC, telling his crew that his grandmother had died, Lulzsec accepted it, though in retrospect something was different about him. "We immediately saw a change in his attitude," recalls one former colleague. "He started really pushing the revolutionary rhetoric, trying to band everyone together by calling us 'brothers' and saying we were 'all in this together' and we were 'family.'"

On June 19th, 2011, Sabu announced the launch of Operation Antisec, "the biggest, unified operation amongst hackers in history." The declaration got Hammond's attention, as did Antisec's tantalizing lists of targets, including "banks and other high-ranking establishments." Stuck in his Chicago house on a curfew, barred from real-life activism, Hammond couldn't help himself. "It was like call-and-response," he says.

By the late spring of 2011, rumors were rampant within the hacktivist underground that the FBI, replicating the notorious Cointel program of the 1960s, had heavily infiltrated Anonymous chat rooms. Within Sabu's tight circle, paranoia was particularly strong, and it intensified exponentially as the 50 days of Lulz drew to an end.

In late June, Lulzsec released hundreds of pages of sensitive information belonging to Arizona law enforcement accompanied by a lengthy announcement posted online titled "Chinga la Migra" – Fuck the Police. If the FBI's assumptions are correct, this was Hammond's first official criminal act as a member of Anonymous – and it was a radical departure from what had come before.

The statement led off with an illustration of an AK-47 and the slogan "Off the pigs." The data dump – hundreds of private intelligence bulletins, training manuals, personal e-mails, names, phone numbers, addresses and passwords belonging to Arizona law enforcement, including documents pertaining to the border patrol and counterterrorism efforts, and the use of confidential informants – was made in protest of the "racial profiling anti-immigrant police state that is Arizona."

After Chinga la Migra #1, there was Chinga la Migra #2, #3 and #4 – all directed at Arizona, and later Texas, law enforcement; each one more radical sounding than the last. "Yes we're aware that [releasing the personal information of police officers] risks their safety, those poor defenseless police officers who lock people up for decades, who get away with brutality and torture . . . who make and break their own laws as they see fit," one missive read. "We are making sure they experience . . . the same kind of violence and terror they dish out on an every day basis." It concluded: "We're not stopping until every prisoner is freed and every prison is burned to the ground."

Some Antisec members complained about the radical message. In her book on the rise and fall of Lulzsec, We Are Anonymous, author Parmy Olson recounts how some members squirmed under this new ideological rhetoric. Topiary, Lulzsec's longtime scribe, who had written every press release but these, was particularly shocked. "We don't want to get police officers killed," he told another Lulzsec member. "That's not my kind of style."

But Sabu was fine with the new rhetoric. "This is anarchy," he told a colleague who worried the statements might turn people off from getting involved just at the time Anonymous was hoping to draw more people in. "The fact that we attack governments and corporations means that we don't give a fuck about what others think."

Sabu proudly declared Antisec to be a revolutionary movement and urged his tens of thousands of Twitter followers to join the cause. "Rise Up. Resist," he posted, one of many virtual calls to war. No one doubted his authority or sincerity. "He was Sabu," says one close associate. Even after some of his Lulzsec colleagues were arrested – including Topiary, who turned out to be an 18-year-old British citizen named Jake Davis – his supporters stayed true, as he did to them. "Thank those fallen Anons for taking the hits that will give the rest of you another day to fight," he tweeted in July.

Sabu began working closely with a new, far quieter player in Antisec: a behind-the-scenes operator known to the larger crew as "anarchaos," though the elite hackers with whom he worked called him "sup_g." Highly dedicated, he was "basically the perfect storm of know-how, drive and ideology," says one former activist. "He was by far the most knowledgeable hacker in Antisec, and he wasn't afraid to get his hands dirty." Together, he and Sabu were a formidable duo, though Sabu wasn't taken very seriously by many black hats. "People in the scene treated him like he was just a talking head," says one Anon. "I never felt that he was good for much other than networking."

Most experienced hackers knew that Sabu wasn't as talented as he purported to be. He had not, for example, hacked HBGary, as he claimed, but had only "social engineered" a password out of the company's IT security manager. More troubling were persistent rumors of his having been compromised, even possibly arrested, after he was "doxed" by Jennifer Emick. But the newest member of Sabu's inner circle didn't seem to care. "Sup_g wasn't very interested in all the drama. He just wanted action," says one Antisec hacker. "But the thing is, you need to keep track of the drama in Anonymous. Many times, following the drama can save your life."

The hackers of Antisec followed a strict code, often working in pairs and asking few questions of one another. Sup_g in particular seemed obsessed with his security, says one Anon who worked with him. "He gave very little personal information, was very adamant, even in private chats, about keeping stuff locked down until it was meant to be public – if it was ever meant to be public."

Like everyone else, he changed his nicknames frequently – "To make it more confusing to outside eyes," says one hacker – and could be brutal to those who got careless and called him by a previous name. But sup_g was far more cavalier in public channels. Though no one had claimed personal authorship of the Chinga la Migra statements, one longtime activist who read the postings connected them to a number of nicknames – notably "burn," a "straight-up anarchist-communist militant" – who had expressed many of the same sentiments, often in nearly identical language, on public IRC channels. Before long, "burn," along with "anarchaos" and two other nicknames, "o" and "credible threat," were the loudest and most passionate voices in the virtual world of IRC. Whomever was using these handles knew the finer points of finding food in dumpsters, had been in and out of jail, and was versed in anarchist theory as well as militant black-bloc tactics, having spent "upwards of a decade propagandizing for the people." And he wasn't afraid of being caught. "Prison's not bad," he said. "You do your time like a warrior, and emerge more trained and disciplined than before."

Other hackers grew concerned. "There was a point there where he started to just feel really proud about what he was doing," says one of sup_g's closest colleagues in Antisec, a hacker who would like to be known as "CC3." "Many times I said to him, 'Stay hidden. Don't show up too much on public channels.' " Sup_g assured him his security protocols were tight. "I said to him once, 'Please tell me you left the U.S.' and he said yes, he'd moved out. He said he was changing houses every week."

Hammond, of course, hadn't left Chicago. "I was in jail again," a persona named "tylerknowsthis" wrote in an August 2011 chat. "A dozen pigs raided my house and arrested me for a bag of sage – yes, sage." And, he added, he'd also "beaten a weed case" just seven months earlier.

Though Hammond refuses to admit that he ever used any of the nicknames attributed to him, events in his own life track these chat room posts. He had been arrested seven months earlier for pot possession and held for three weeks in the Cook County jail while awaiting the result of the drug test. Then in July 2011, Hammond's house was raided again: This time it wasn't just the police but also the FBI. "They questioned me and my roommates, none of us talked, so I don't know what they were investigating," he says. He spent another three weeks in jail for a bag of sage, which the feds had mistaken for marijuana.

When he got out, Hammond began to spend time with Occupy Chicago, and "burn" became active in OpBART, an Anonymous attack on the Bay Area Rapid Transit System. "Burn" also involved himself in Anonymous' dedicated Occupy Wall Street channel, which tried to strategize protests around the country. One day, Hammond's real and online lives collided when he met a digital-rights activist named Peter Fein, who met up with some protesters at Occupy Chicago. "I went down to Occupy one day, and I got to talking to people and mentioned that I did stuff with Anonymous. And this guy blurted out, 'Oh, yeah, I'm in Lulzsec,' " he says. "I thought, OK, either you're lying or an idiot. And that turned out to be Jeremy."

Hammond, who never told Fein his name, handed him some anarchist literature and two old issues of Hack This Zine, and began to talk about hacktivism. "I thought he was just another crazy from Anon. My sense was that he wanted recognition and credit, and you can't do that and be 'Anonymous,'" Fein says.

After Hammond was arrested and Fein saw his picture, he wasn't surprised. "From the moment I met Jeremy, I got the sense that he expected to go back to jail."

As the Occupy movement became a national phenomenon last fall, Antisec hackers stepped up their activity: exposing sensitive documents belonging to more than 70 law-enforcement agencies, including the International Association of Chiefs of Police, in retaliation for the police crackdown against Occupy protesters. They even hacked the gmail accounts of a California cybercrime investigator, some of whose e-mails detailed the methods that cybercrime units use to catch hackers.

By this time, sup_g had become the dominant voice of the 10 or so core members of Antisec, and the most indefatigable member of the team. Most of the work of the group now went through him, including the writing of nearly all the press releases, as Sabu became increasingly unreliable. That summer, Sabu had disappeared from the Internet entirely after a rival hacker released his own dossier on Monsegur. In September, he returned, blazing with an even greater urgency. "Every room I was in that he was in, he was very pressure-oriented to get shit done," says one former Antisec member. "And it needed to be done within the day or he would start yelling at people."

Yet Sabu rarely got involved in actual hacks. By November, even Hammond had grown suspicious, says CC3, and he and several other Antisec members began to distance themselves. "We got tired of seeing Sabu never get his hands dirty," says CC3. "And at some point a few of us sat together in an IRC chat room and asked, 'Who has ever seen Sabu hack anything?'" No one had.

But Sabu's core talent had always been as a fixer: bringing information provided to him by other hackers to people like sup_g, who could exploit it to the fullest. According to CC3, last November a hacker nobody knew told Sabu about a security hole in the website of a company called Strategic Forecasting Inc. Sabu handed that information to his team. Over the next few weeks, as his crew worked away, sup_g checked in with Sabu, giving him status updates. Needing a place to store the pilfered data, sup_g also accepted Sabu's offer to provide an external server, in New York. When the transfer was complete and Stratfor's website defaced, Sabu took to Twitter to announce the hack, and by Christmas the attack was all over the news.

The following day, Sabu logged on to IRC, entered a special chat room dubbed "#lulzmas" and sent a message to sup_g.

"Yo yo," he said.

"Hey, homboii," sup_g replied. "I been going hard all night."

"I heard we're all over the newspapers," said Sabu. "You motherfuckers are going to get me raided. HAHAHAAHA."

"Dude, it's big," sup_g said.

"If I get raided anarchaos," Sabu said, "your job is to cause havok [sic] in my honor." He added a heart – perhaps to deflect from the fact that he'd just casually linked one nickname with another. It was something he'd done a number of times: call sup_g by another name, which always prompted his partner to leave the chat. But this time, for unknown reasons – lapse of judgment, even the possibility that for just a moment he forgot who he was – sup_g didn't even flinch.

"It shall be so," he said.

On the warm summer night of June 7th, 2011, two weeks before Sabu began recruiting for Antisec, Hector Xavier Monsegur, was at home in his Avenue D apartment when he heard a knock at the door. Outside were two FBI agents claiming they had enough incriminating evidence pertaining to Monsegur's Anonymous hacking, as well as to a variety of real-life petty crimes, to put him away for 122 years.

Within hours Sabu had cut a deal and agreed to work for the FBI, rolling over on his Lulzsec comrades. Over the following nine months, he helped the government gather information, often working "literally around the clock" to build the case, according to official documents. He was, in the words of the federal prosecutor, a model informant.

News of Monsegur's role as a snitch broke on the same day as the news of Hammond's arrest. At first Anons denied that such a betrayal could be true. But after Sabu's indictment and guilty plea were leaked to the press, shock quickly turned to anger, and sadness. "I just can't bring myself to hate him," says one Antisec hacker. "We will never know the extent that the FBI went to turn him into a traitor."

Some members of Anonymous would say they knew it all along. "I always sensed he was a fraud," Christopher Doyon, an Anon who goes by the name "Commander X," told me last spring. "All of that was put on to please the feds, and all I can say is that they goddamn better put the fucker in witness protection," he adds. "What really makes me want to kill him is that he did all of it so he could send these poor kids to prison."

Not everyone was trapped, however. According to several Anons, Sabu protected those he knew wouldn't be useful to the FBI. One Antisec member recalls that Sabu encouraged him and a number of others to leave the Antisec channel "because, to use his words, 'you will be charged with conspiracy.' He said that to all of us who weren't involved in hacking."

Since the revelations, a few Anons have put together an Antisec timeline, convincingly arguing that given the date of Monsegur's arrest and conversion, June 7th-8th, 2011, and his subsequent announcement of his new hacker movement on June 19th, Antisec must have been created under the FBI's watch, intended as a honey pot to lure in a myriad of political hackers, most prominently Jeremy Hammond. "I think when his name popped up in this investigation, the FBI rubbed their hands together in glee," says cyberinvestigator Steve Rambam. "They were endlessly delighted when he fell into the net."

The government's case against Hammond revolves around the nicknames he is said to have used at various times over the past year. (Neither the Justice Department nor the FBI, citing the ongoing nature of the investigation, will comment beyond their initial press release announcing the arrests.) Hammond's attorneys tell me they are in possession of nearly a terabyte of discovery material – some 20,000 bankers boxes, the equivalent of half a research library of reading material – with potentially more to come. But Hammond has been effectively locked out of his own defense. He can only view the material in the presence of his lawyers and he cannot use prison computers to do legal research, even though they are not connected to the Internet ("It's like they think he's some kind of wizard who can magically get online no matter what," says one person associated with the case). It could take years for him to review all of the discovery material.

So far, all of the alleged Lulzsec hackers, who have been arrested have pleaded guilty or are soon expected to. Hammond has not, but even if he were to accept a plea, it is likely he will spend many years in prison. Two days after Hammond's arrest, on March 7th, 2012, FBI Director Robert Mueller, who has frequently said that cyberthreat will soon overtake terrorism as the bureau's top priority, warned Congress that terrorists might recruit politically motivated hackers like Hammond into launching cyberattacks against the U.S. "You want to identify the individuals who are responsible for these crimes, investigate them, prosecute them and put them in jail for a substantial period of time," Mueller said. In early October, Defense Secretary Leon Panetta, arguing for stricter laws against hacking, warned that the country is in a "pre-9/11 moment."

But some worry about what that crackdown will cost. "In this country there is an impenetrable cloud of secrecy over what the government and corporations do," says Michael Ratner, president emeritus of the Center for Constitutional Rights, and the attorney for Julian Assange, whose name was mentioned more than 2,000 times in the Stratfor e-mails. "Whatever technical crimes the government claims have been committed must be weighed against the good that comes from lifting the veil on corporate and government spying and corruption. We should not punish the courageous people that exposed it."

As the information contained within the Stratfor e-mails continues to leak out – the most recent suggests that the U.S. worked with the Mexican Sinaloan cartel to limit the violence in Mexico, while also allowing drugs to flow over the border – Antisec went quiet with the exception of two hacks, most recently in September, when Antisec re-emerged to announce the leak of over a million Apple user IDs they claimed were stolen from an FBI laptop. In their statement, written without the panache of those Hammond is believed to have penned, the group paid tribute to its jailed comrade as an "ideological [sic] motivated political dissident" in the same camp as Bradley Manning. Then the group went quiet again – and may remain so for a while. "We're focusing less on defacement and more on quietly taking over infrastructure," says the hacktivist who calls himself CC3. "And right now, the FBI doesn't have a clue about what we're doing – which is good."

Although Hammond's contribution was huge, some within Anonymous were happy to see him go. ("I wonder if Sabu did us a favor by cleansing Anonymous of the more radical elements," one member told me.) But even those who disagreed with Jeremy Hammond appreciate his value; those who sided with him feel his loss even more poignantly. "He pissed a lot of people off with his anarchist talk, but he was the real thing," says CC3. "He fought for what he believed his whole life. He was an idealist who even after being jailed, kept fighting at every occasion, and he never betrayed himself. Not many people can say they have never betrayed themselves."

This story is from the November 8th, 2012 issue of Rolling Stone.

Postscript:

On November 20th, 2012, Jeremy Hammond, who had been held in a Manhattan jail for more than eight months since his arrest in March, was denied bail in a federal court. The hearing before Judge Loretta Preska was dominated by an impassioned plea by Hammond's defense counsel. "There is no way I can prepare for this trial while this man is in prison," his lawyer, Elizabeth Fink, a well-known civil rights attorney, stated, noting the hundreds of thousands of pages of discovery – much of it highly technical forensic material – that she found almost completely incomprehensible.

Preska, however, was unmoved – even with defense assurances that Hammond, who doesn't hold a passport, was not a flight risk and would remain under house arrest at the home of Manhattan lawyer Michael Steven Smith, an "officer of the court" who was willing to guarantee that Hammond wouldn't have access to a computer. But the chance that Hammond might get access "poses a very substantial danger to the community," Preska said, as did his "lack of regard for legal authority." For now, he remains at the Metropolitan Correctional Center, where he will likely stay until his trial, slated for late 2013, though some believe it may happen much later.

But Hammond may yet have another chance, thanks to Anonymous, which responded to the verdict by "doxing" Preska, releasing personal information on her as well as her husband, Thomas J. Kavaler, a partner at the Manhattan law firm Cahill Gordon & Reindel. According to the leaked material, Kavaler, through his firm, was a client of the intelligence firm Stratfor and a victim of the Anonymous attack, all of which raises significant questions about Preska's objectivity. On December 6th, Hammond's attorney filed a motion demanding that Preska, who also worked at Cahill Gordon prior to her confirmation as a judge, recuse herself. "This personal connection to the damage allegedly inflicted by Mr. Hammond," the motion said, "is more than enough to raise the possibility in the mind of an objective observer that this Court could not be impartial in this case."